在python中获取当前位置所在的行号和函数名
对于python，这几天一直有两个问题在困扰我:
1.python中没办法直接取得当前的行号和函数名。这是有人在论坛里提出的问题，底下一群人只是在猜测python为什么不像__file__一样提供__line__和__func__，但是却最终也没有找到解决方案。
2.如果一个函数在不知道自己名字的情况下，怎么才能递归调用自己。这是我一个同事问我的，其实也是获取函数名，但是当时也是回答不出来。
但是今晚！所有的问题都有了答案。
一切还要从我用python的logging模块说起，logging中的format中是有如下选项的:
%(name)s
Name of the
logger (logging channel)
%(levelno)s
Numeric
logging level for the message (DEBUG, INFO,
WARNING,
ERROR, CRITICAL)
%(levelname)s
Text
logging level for the message ("DEBUG", "INFO",
"WARNING",
"ERROR", "CRITICAL")
%(pathname)s
Full pathname
of the source file where the logging
call was
issued (if available)
%(filename)s
Filename
portion of pathname
%(module)s
Module
(name portion of filename)
%(lineno)d
Source line
number where the logging call was issued
(if
available)
%(funcName)s
Function
name
%(created)f
Time when
the LogRecord was created (time.time()
return
value)
%(asctime)s
Textual time
when the LogRecord was created
%(msecs)d
Millisecond
portion of the creation time
%(relativeCreated)d Time in milliseconds when the LogRecord was
created,
relative to
the time the logging module was loaded
(typically at
application startup time)
%(thread)d
Thread ID
(if available)
%(threadName)s
Thread name
(if available)
%(process)d
Process ID
(if available)
%(message)s
The result
of record.getMessage(), computed just as
the record is
emitted也就是说，logging是能够获取到调用者的行号和函数名的，那会不会也可以获取到自己的行号和函数名呢？
我们来看一下源码，主要部分如下:
def currentframe():
"""Return the frame object
for the caller's stack frame."""
try:
raise
Exception
except:
return
sys.exc_info()[2].tb_frame.f_back
def findCaller(self):
"""
Find the stack frame of the
caller so that we can note the source
file name, line number and
function name.
"""
f = currentframe()
#On some versions of
IronPython, currentframe() returns None if
#IronPython isn't run with
-X:Frames.
if f is not None:
f =
f.f_back
rv = "(unknown file)", 0,
"(unknown function)"
while hasattr(f,
"f_code"):
co =
f.f_code
filename =
os.path.normcase(co.co_filename)
if filename
== _srcfile:
f =
f.f_back
continue
rv =
(co.co_filename, f.f_lineno, co.co_name)
break
return rv
def _log(self, level, msg, args, exc_info=None,
extra=None):
"""
Low-level logging routine
which creates a LogRecord and then calls
all the handlers of this
logger to handle the record.
"""
if _srcfile:
#IronPython
doesn't track Python frames, so findCaller throws an
#exception on
some versions of IronPython. We trap it here so that
#IronPython
can use logging.
try:
fn, lno,
func = self.findCaller()
except
ValueError:
fn, lno,
func = "(unknown file)", 0, "(unknown function)"
else:
fn, lno, func
= "(unknown file)", 0, "(unknown function)"
if exc_info:
if not
isinstance(exc_info, tuple):
exc_info =
sys.exc_info()
record =
self.makeRecord(self.name, level, fn, lno, msg, args, exc_info,
func, extra)
self.handle(record)我简单解释一下，实际上是通过在currentframe函数中抛出一个异常，然后通过向上查找的方式，找到调用的信息。其中
rv = (co.co_filename, f.f_lineno,
co.co_name)的三个值分别为文件名，行号，函数名。(可以去来看一下代码中几个系统函数的说明)
OK，如果已经看懂了源码，那获取当前位置的行号和函数名相信也非常清楚了，代码如下:
#!/usr/bin/python
# -*- coding: utf-8 -*-
''''''
import sys
def get_cur_info():
"""Return the frame object
for the caller's stack frame."""
try:
raise
Exception
except:
f =
sys.exc_info()[2].tb_frame.f_back
return (f.f_code.co_name,
f.f_lineno) def
callfunc():
print
get_cur_info()
if __name__
== '__main__':
callfunc()输入结果是:
('callfunc', 24)
